The present invention relates to a liquid tank and a tubular structure for liquid tank suitable for a fuel cell, a fuel cell using the same, and an electronic device containing such a fuel cell.
A fuel cell system generally has therein a tank to store a fuel. In a fuel tank of a fuel cell system mounted on a portable device, it is requested to suction the liquid in the tank to the last drop even when the tank is tilted to any angle. To meet such a request, in the past, for example, as illustrated in FIG. 12, a fuel tank 120 having a double structure in which a liquid fuel 121 is enclosed into a sac-like container 120A and the container is covered with an outer case 120B in the shape of a rectangular solid and the like are used. However, in this method, as the fuel is suctioned, the container is gradually deflated. Thus, a large suction pressure to suction the fuel to the last drop is necessitated, resulting in a problem that the fuel is not able to be used up to the last virtually. Further, due to the double structure composed of the sac-like container 120A and the outer case 120B, there is a problem that a dead space 122 is generated.
For example, in Patent Document 1, a description is given that an X-shaped suction structure composed of a porous material is provided in a container, and a liquid fuel is suctioned by capillary action.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-539364 (claim 1, claim 157, and FIG. 25)